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Science China Technological Sciences 2013年第3期56卷 554-557页

作者： LU LinLin SHI YueChun chen xiangfei National Laboratory of Solid State Microstructures & School of Engineering and Applied Sciences Nanjing University

A 1.3 μm distributed feedback(DFB) semiconductor laser with equivalent λ/4 phase shift based on reconstruction equivalent chirp(REC) technique is numerically studied and experimentally *** simulation results show that the 1.3 μm DFB laser with equivalent λ/4 phase shift based on the REC technique performs the same as that of actual λ/4 phase shift DFB laser,with nearly the same P-I curves,the internal power distributions and the output ASE *** with the traditional λ/4 phase shift DFB laser,the REC based laser only changes the sampling structures with the uniform seed waveguide grating instead of the actual grating *** a result,the fabrication of such laser will be very *** this paper,we successfully fabricated the 1.3 μm DFB laser based on the REC technique for the first time to the best of our knowledge.

关键词： λ/4 phase shift distributed feedback(DFB) semiconductor laser reconstruction equivalent chirp(REC) technique

Transient mode competition in directly modulated DFB semiconductor laser

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Science China(Physics,Mechanics & Astronomy) 2015年第12期58卷 187-192页

作者： XIAO RuLei SHI YueChun ZHENG JiLin ZHANG YunShan ZHENG JunShou chen xiangfei National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences Nanjing University Photonics Information Technology Laboratory Institute of Communication Engineering PLA University of Science and Technology

A new effect of transient mode competition in directly modulated DFB laser based on equivalent phase-shift （EPS） technique is presented and studied. Since there are multi-order reflections in EPS structure and if the 0th order subgrating is properly de- signed, the transient lasing of 0th order will occur during the rising time of the injection current. As a result, transient mode competition between -lst order （main mode） and 0th order will occur accordingly. This can consume redundant carrier and suppress the transient relaxation oscillation, which may be applied in some areas like on-off switching modulation of DFB semiconductor lasers. As an example, an equivalent n phase shift （n-EPS） is carefully designed to realize the effect. In such a laser the 0th order wavelength is in the margin of the material gain region and the -1st order wavelength is around the gain peak, while the stable single longitudinal mode （SLM） operation of the -lst order is guaranteed. The simulation investigation is performed. Good results with suppressed relaxation oscillation and 1.25 Gb/s directly on-off modulation （32 dB extinction ratio） are demonstrated. We believe it provides a new kind of method for on-off switching with high extinction ratio and weak relaxation oscillation.

关键词： DFB semiconductor laser mode competition relaxation oscillation sampled grating

Periodic structural defects in Bragg gratings and their application in multiwavelength devices

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Photonics Research 2016年第2期4卷 35-40页

作者： Rulei Xiao Yuechun Shi Renjia Guo Ting chen Lijun Hao xiangfei chen National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences Nanjing University

In this paper, we present the finding that periodic structural defects(PSDs) along a Bragg grating can shift the Bragg wavelength. This effect is theoretically analyzed and confirmed by numerical calculation. We find that the Bragg wavelength shift is determined by the defect size and the period of the defects. The Bragg wavelength can be well tuned by properly designing the PSDs, and this may provide an alternative method to fabricate grating-based multiwavelength devices, including optical filter arrays and laser arrays. In regards to wavelength precision, the proposed method has an advantage over the traditional methods, where the Bragg wavelengths are changed directly by changing the grating period. In addition, the proposed method can maintain grating strength when tuning the wavelength since only the period of defects is changed. This will be a benefit for devices such as arrays.

关键词： Periodic structural defects in Bragg gratings and their application in multiwavelength devices RGS

Numerical study of three phase shifts and dual corrugation pitch modulated(CPM) DFB semiconductor lasers based on reconstruction equivalent chirp technology

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Chinese Science Bulletin 2010年第35期55卷 4083-4088页

作者： SHI YueChun TU XingHua LI SiMin ZHOU YaTing JIA LingHui chen xiangfei Microwave-Photonics Technology Laboratory National Laboratory of Microstructures Nanjing University Nanfing 210093 China Department of Electronic Science and Engineering Nanjing University Nanjing 210093 China Microfluidics and Optics Technology Research Center College of Opto-Electronic Engineering Nanjing University of Posts and Telecommunication Nanfing 210003 China

A distributed feedback(DFB) semiconductor laser with three phase shifts based on reconstruction equivalent chirp(REC) technology is proposed and investigated *** the combination of multiple phase shifts and corrugation pitch modulated(CPM) structure,we also propose a novel and more complex structure named dual CPM,which has a flatter light power distribution along the laser cavity compared with the true double phase shifts DFB laser diode(LD),while the P-I curves are nearly the *** proposed dual CPM structure is also designed and analyzed based on REC *** simulation results show that,the DFB semiconductor laser with complex structure such as phase shifts,or even arbitrary variation of the grating period can be achieved equivalently and easily by changing the sampling *** its external characteristics are almost the same as those DFB lasers with true phase shifts,or true arbitrary variation of the grating *** key advantage of the REC technology is that it varies only the sampling structure and keeps the seed grating(actual grating in sampling structure) period *** its fabrication needs only low-cost and standard holographic exposure *** we believe this method can achieve the high-end and low-cost DFB LD for mass production.

关键词：半导体激光器等效采样拍摄技术数值研究 CPM 啁啾重构基础

Research Progress on Ocular Surface Changes after Femtosecond Laser Small IncisionLenticule Extraction

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Eye Science 2015年第1期30卷 48-52页

作者： xiangfei chen Yan Lu Chunhong Wang Zhenping Huang Medicine School of Nanjing University Nanjing General Hospital of Nanjing Military Command of PLA

The femtosecond laser has a number of advantages,.such as short pulse time,.high instantaneous power,.high repetition rate, low monopulse energy, and small thermal effect. Femtosecond laser-assisted small incision lenticule extraction(SMILE) is becoming the new direction in refractive surgery,and the ocular surface changes after SMILE are attracting increasingly more attention. This article reviews adverse effects,including dry eye, injury of corneal nerves, and ocular surface inflammation,.occurring after SMILE.

关键词：飞秒激光 SMILE 提取脉冲时间瞬时功率高重复率脉冲能量激光辅助

Compact packaging for multi-wavelength DML TOSA

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Chinese Science Bulletin 2014年第20期59卷 2387-2390页

作者： Jiasheng Wang Yu Liu xiangfei chen Jianguo Liu Ninghua Zhu Institute of Semiconductors Chinese Academy of Sciences National Laboratory of Microstructures Nanjing University

A compact multi-wavelength hybrid-integrated directly-modulated distributed-feedback laser(DML)transmitter optical sub-assembly(TOSA)has been achieved in our *** 8-channel distributed feedback(DFB)lasers are monolithically integrated based on the reconstruction-equivalent-chirp(REC)*** the high-density and high-speed packaging technique,the laser array and a multi-mode interference(MMI)multiplexer are assembled in the *** channel spacing of the TOSA is 200 GHz between adjacent *** meets the 8 9 12.5 Gb/s operation demand and gives rather low channel crosstalk of less than-25 *** compact TOSA is of effective cost and shows good stability for mass production,which is expected to improve the performance of devices in access networks,data centers and supercomputing.

关键词：包装技术 DML 多波长分布反馈激光器多路转换器超级计算机直接调制混合集成

Experimental demonstration of a photonic spiking neuron based on a DFB laser subject to side-mode optical pulse injection

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Science China(Information Sciences) 2024年第3期67卷 271-280页

作者： Shuiying XIANG Shuang GAO Yuechun SHI Yuna ZHANG Ziwei SONG Xingxing GUO Yahui ZHANG Yuxin MA xiangfei chen State Key Laboratory of Integrated Service Networks Xidian University Yongjiang Laboratory College of Engineering and Applied Sciences Nanjing University

We proposed and experimentally demonstrated a simple and novel photonic spiking neuron based on a distributed feedback(DFB) laser subject to side-mode optical pulse injection(SMOPI). The DFB laser chip is designed and fabricated based on asymmetric equivalent π phase shift(π-EPS) with the reconstruction-equivalent-chirp(REC) technique. Under side-mode continuous-wave(CW) optical injection,excitability pulse was experimentally observed during the dominant mode switching process due to the injection-locked effect. Based on the transition between the excitability regime and the side-mode injection locking effect, the controllable and repeatable neuron-like spiking response can be realized when external stimulus pulses are electro-optically modulated on the CW optical carrier. The experimental results show that the spike threshold, temporal integration, and refractory period, which are important spike processing mechanisms in biological neurons, can all be achieved in the optically-injected DFB laser. The experimental findings are also verified numerically with a rate equation model that considers the SMOPI. To the best of our knowledge, this is the first experimental demonstration of a photonic spiking neuron based on a DFB laser subject to SMOPI, which holds promise for realizing large-scale photonic spiking neuron arrays for hardware photonic spiking neural network chips.

关键词： neuromorphic photonics photonic spiking neuron DFB laser side-mode optical pulse injections

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Nonlinear neural computation in an integrated FP-SA spiking neuron subject to incoherent dual-wavelength optical pulse injections

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Science China(Information Sciences) 2023年第12期66卷 299-300页

作者： Ziwei SONG Shuiying XIANG Xingxing GUO Shuang GAO Biling GU Dianzhuang ZHENG xiangfei chen Yuechun SHI State Key Laboratory of Integrated Service Networks State Key Discipline Laboratory of Wide Bandgap Semiconductor TechnologyXidian University 2. Yongjiang Laboratory Key Laboratory of Intelligent Optical Sensing and Manipulation Ministry of EducationNational Laboratory of Solid State MicrostructuresCollege of Engineering and Applied SciencesInstitute of Optical Communication EngineeringNanjing University

Photonic nonlinear computation is the critical cornerstone of photonic neuromorphic computing. As one of the key information function units in the photonic spiking neural networks, the photonic spiking neurons are responsible for the nonlinear computation of the network. Recently, the neuron-like nonlinear computation of the photonic spiking neuron has attracted considerable attention.

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Experimental demonstration of λ/8 DFB semiconductor laser array for 1.3 μm CWDM system

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Science China(Technological Sciences) 2014年第9期57卷 1769-1772页

作者： LU LinLin HUANG Long SHI YueChun GUO RenJia LIU Rui LI LianYan LI SiMin chen xiangfei National Laboratory of Microstructures & School of Engineering and Applied Sciences Nanjing University

In this article,we report the first experimental demonstration of an eight-wavelength λ/8 phased-shifted laser array based on the REC technique in the 1.3 μm wavelength *** results exhibit good linearity of lasing wavelength with+/-0.35 nm wavelength *** SLM property was ensured with SMSRs all larger than 38 ***,the directmodulation performance was also *** experimental results show that the modulation bandwidth can reach up to 13GHz even at the small injection current of 40 mA and the measured spurious-free dynamic range(SFDR)is up to 87 dB/Hz2/3,which shows good *** measurements show that REC-based λ/8 phased-shifted laser array has good modulation performance and it may find potential application in actual fiber-optic systems.

关键词： λ/8 phase shift DFB semiconductor laser array Reconstruction-Equivalent-Chirp (REC) technique

Experimental demonstration of the three-phase-shifted DFB semiconductor laser with buried heterostructure using common holographic exposure

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Science China(Technological Sciences) 2014年第11期57卷 2231-2235页

作者： LU LinLin CAO BaoLi ZHANG LiBo TANG Song LI LianYan LI SiMin SHI YueChun chen xiangfei National Laboratory of Microstructures & School of Engineering and Applied Sciences Nanjing University

In this article, we report the first experimental demonstration of the three-phase-shifted （3PS） DFB semiconductor laser with buried heterostructure based on the Reconstruction-Equivalent-Chirp （REC） technique. The simulation results show that the performances of the equivalent 3PS DFB semiconductor laser are nearly the same as those of the true 3PS laser. Compared with the quarter-wave-phase shift （QWS） DFB semiconductor laser, the 3PS DFB semiconductor laser shows better single-longitude-mode （SLM） property even at high injection current with high temperature. However, it only changes the ~un-level sampling structures but the seed grating is uniform using the REC tech- nique. Therefore, its fabrication cost is low.

关键词： three-phase-shifted structure DFB semiconductor laser Reconstruction-Equivalent-Chirp (REC) technique